5902 Organometallics, Vol. 29, No. 22, 2010
Gluyas et al.
-1.65 (2C, SiCH3), 18.7 (CCH3), 24.5 (CH(OH)CH3), 65.1
(CH(OH)CH3), 129.2 (C-4), 133.9 (C-6), 134.6 (C-7), 145.3
(C-5), 146.5 (C-3a or C-7a), 147.3 (C-3a or C-7a). 29Si NMR
(99.4 MHz, [D6]DMSO): -53.6, -14.0, -13.9. EI-MS: m/z (%)
308 (37) [Mþ], 293 (11) [Mþ - CH3], 73 (100). Anal. Calcd for
C15H28OSi3: C, 58.37; H, 9.14. Found: C, 58.45; H, 9.03.
Synthesis of 2-(1,1,2,2,3,3,6-Heptamethyl-1,2,3-trisilaindan-5-
yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5). A 0.01 M solu-
tion of iodine in acetonitrile (40.0 mL, 400 μmol of iodine) was
added to zinc powder (256 mg, 3.92 mmol) in a single portion at
20 °C. The mixture was then stirred at this temperature until the
brown coloration disappeared and a gray suspension was
observed. The temperature was maintained at 20 °C, and compound
7 (4.48 g, 20.0 mmol), compound 11 (4.64 g, 27.9 mmol), and a
0.1 M solution of cobalt(II) iodide in acetonitrile (10.0 mL 1.00
mmol of CoI2) were then added sequentially in single portions.
The resultant dark brown solution was stirred at 20 °C for 30
min, whereupon GC analysis indicated complete consumption
of the starting materials. The reaction mixture was then passed
through a short silica column (eluent, n-hexane/ethyl acetate
(80:20 (v/v)). The brown residue resulting following removal of
the solvent was purified by flash column chromatography (silica
gel; eluent, n-hexane/ethyl acetate (96:4 (v/v))). The relevant
fractions (GC analysis) were combined and concentrated under
reduced pressure to give a yellow oil. This was crystallized from
methanol (-30 °C), followed by recrystallization, once from
methanol (-30 °C) and twice from n-hexane (20 °C), to afford 5
as a colorless crystalline solid in 25% yield (1.94 g, 4.97 mmol);
mp 287 °C (dec). 1H NMR (500.1 MHz, CDCl3): δ 0.26 (s, 6 H,
SiCH3), 0.30 (s, 6 H, SiCH3), 0.33 (s, 6 H, SiCH3), 1.33 (s, 12 H,
C(CH3)2), 2.54 (s, 3 H, CCH3), 7.37 (s, 1 H, H-4), 7.97 (s, 1 H,
H-7). 11B NMR (160.5 MHz, CDCl3): δ 30.6. 13C NMR (125.8
MHz, CDCl3): δ -8.2 (SiCH3), -1.9 (SiCH3), -1.6 (SiCH3),
22.6 (CCH3), 25.0 (C(CH3)2), 83.4 (C(CH3)2), 14.7 (C-4), 140.6
(C-7), 144.5 (C-3a or C-7a), 145.7 (C-3a or C-7a), 154.1 (C-6),
C-5 not detected. 29Si NMR (99.4 MHz, CDCl3): -53.3, -13.5,
-13.3. EI-MS: m/z (%) 390 (84) [Mþ], 375 (48) [Mþ - CH3], 73
(100). Anal. Calcd for C19H35BSi3O2: C, 58.43; H, 9.03. Found:
C, 58.65; H, 8.70.
202.2 (C(O)CH3). 29Si NMR (99.4 MHz, CDCl3): -33.2 (CSiSi),
1.1 (CSiO), 8.9 (SiSiO). NMR data for 6b: H NMR (500.1
1
MHz, CDCl3): δ 0.29 (s, 6 H, SiSi(CH3)2O), 0.33 (s, 12 H,
CSi(CH3)2Si and CSi(CH3)2O), 2.49 (s, 3 H, CCH3), 2.58 (s, 3 H,
C(O)CH3), 7.28 (s, 1 H, H-8), 7.82 (s, 1 H, H-5). 13C NMR (125.8
MHz, CDCl3): δ -2.3 (CSi(CH3)2Si), 1.9 (CSi(CH3)2O), 1.98
(SiSi(CH3)2O), 21.5 (CCH3), 29.6 (C(O)CH3), 134.0 (C-5), 136.8
(C-8), 136.9 (C-8a), 137.8 (C-4a), 142.8 (C-6), 151.0 (C-7), 202.3
(C(O)CH3). 29Si NMR (99.4 MHz, CDCl3): -33.4 (CSiSi), 1.0
(CSiO), 9.0 (SiSiO). EI-MS: m/z (%) 322 (10) [Mþ], 307 (100)
[Mþ - CH3]. Anal. Calcd for C15H26O2Si3: C, 55.84; H, 8.12.
Found: C, 55.67; H, 8.10. EI-MS (mixture of 6a and 6b): m/z (%)
322 (10) [Mþ], 307 (100) [Mþ - CH3]. Anal. Calcd for C15H26-
O2Si3: C, 55.84; H, 8.12. Found: C, 55.67; H, 8.10.
Synthesis of 1,3-Diethynylhexamethyltrisilane (7). This com-
pound was synthesized from 15 according to ref 13.
Synthesis of Pent-3-yn-2-one (8). This compound was synthe-
sized according to ref 14.
Hex-3-yn-2-one (9). This compound was commercially avail-
able (ABCR). It was distilled prior to use and stored under
argon.
Synthesis of rac-Pent-3-yn-2-ol (10). This compound was
synthesized according to ref 15.
Synthesis of 4,4,5,5-Tetramethyl-2-prop-1-ynyl-1,3,2-dioxa-
borolane (11). This compound was synthesized according to
ref 6b.
Hexamethyldisilane (12). This compound was commercially
available (ABCR) and was used as received.
Synthesis of Chloropentamethyldisilane (13). A mixture of
compound 12 (99.7 g, 681 mmol), chlorotrimethylsilane (81.8
g, 753 mmol), and aluminum trichloride (1.82 g, 13.6 mmol) was
heated to distill off the accruing tetramethylsilane (bp 28 °C,
1 bar) fractionating using a spinning band column. When the rate
of formation of the dichlorinated side product (dichlorotetra-
methyldisilane), as observed by GC, exceeded the rate of con-
sumption of 12, dry acetone (5.00 mL) was added to deactivate
the aluminum trichloride. The distillation was continued to
remove the remaining tetramethylsilane and chlorotrimethylsi-
lane (bp 57-58 °C, 1 bar). Vacuum distillation of the remainder
over a spinning band column afforded 13 in 67% yield (76.0 g,
Synthesis of 1-(1,1,3,3,4,4,6-Heptamethyl-1,3,4-trisilaisochro-
man-7-yl)ethanone (6a) and 1-(1,1,3,3,4,4,7-Heptamethyl-1,3,4-
trisilaisochroman-6-yl)ethanone (6b). A single aliquot of 4 (300
mg, 972 μmol) as a solution in dichloromethane (5 mL) was
added to a stirred 0.1 M solution of Dess-Martin periodinane12
in dichloromethane (11.6 mL, 1.16 mmol) at 20 °C. Stirring was
continued for 150 min, whereupon GC analysis indicated com-
plete consumption of 4. A 1.0 M solution of sodium hydroxide
(5.00 mL, 5.00 mmol) and diethyl ether (20 mL) were added
sequentially, and the reaction mixture was stirred at 20 °C for a
further 15 min. The aqueous layer was separated, extracted with
diethyl ether (2 ꢀ 20 mL), and discarded. The combined organic
extracts were dried over anhydrous sodium sulfate and passed
through a short silica gel column (eluent, n-hexane/ethyl acetate
(10:90 (v/v)). The solvent was removed under reduced pressure,
and the resultant yellow oily residue was purified by RP-MPLC
1
456 mmol) as a colorless liquid; bp 76-77 °C, 170 mbar. H
NMR (500.1 MHz, CDCl3): δ 0.16 (s, 9 H, Si(CH3)3), 0.47 (s, 6
H, Si(CH3)2Cl). 13C NMR (125.8 MHz, CDCl3): δ -2.9
(Si(CH3)3), 2.2 (Si(CH3)2Cl). 29Si NMR (99.4 MHz, CDCl3):
-18.2, 23.9. EI-MS: m/z (%) 166 (23) [Mþ], 151 (27) [Mþ
-
CH3], 131 (35) [Mþ - Cl], 73 (100). 1H NMR data were in good
agreement with those reported in ref 16.
Synthesis of Octamethyltrisilane (14). This compound was
synthesized from 13 according to ref 17.
Synthesis of 1,3-Dichlorohexamethyltrisilane (15). This com-
pound was synthesized from 14 according to ref 18.
Crystal Structure Analyses. Suitable single crystals of 3 and 5
were obtained as described in the respective synthetic procedures.
(eluent, methanol/water (90:10 (v/v)); flow, 23 mL min-1
;
(13) Hamon, P.; Justaud, F.; Cador, O.; Hapiot, P.; Rigaut, S.;
Toupet, L.; Ouahab, L.; Stueger, H.; Hamon, J.-R.; Lapinte, C.
J. Am. Chem. Soc. 2008, 130, 17372–17383.
(14) Coleman, R. S.; Lu, X.; Modolo, I. J. Am. Chem. Soc. 2007, 129,
3826–3827.
(15) Fleming, I.; Takaki, K.; Thomas, A. P. J. Chem. Soc., Perkin
detector wavelength, 240 nm) to yield a very viscous colorless
oil, which solidified on standing, to afford 6 in 48% yield as a
colorless waxy solid (152 mg, 471 μmol; molar ratio 6a:6b,
1
1:0.85). NMR data for 6a: H NMR (500.1 MHz, CDCl3): δ
Trans. 1 1987, 2269–2273.
(16) Einholz, W.; Gollinger, W.; Haubold, W. Z. Naturforsch. B
1990, 45, 25–30.
0.29 (s, 6 H, SiSi(CH3)2O), 0.32 (s, 6 H, CSi(CH3)2Si), 0.34 (s, 6
H, CSi(CH3)2O), 2.51 (s, 3 H, CCH3), 2.56 (s, 3 H, C(O)CH3),
7.44 (s, 1 H, H-5), 7.68 (s, 1 H, H-8). 13C NMR (125.8 MHz,
CDCl3): δ -2.6 (CSi(CH3)2Si), 1.99 (SiSi(CH3)2O), 2.02
(CSi(CH3)2O), 21.5 (CCH3), 29.5 (C(O)CH3), 133.2 (C-8),
137.2 (C-8a), 137.4 (C-4a), 137.6 (C-5), 143.7 (C-7), 150.6 (C-6),
(17) (a) Fritz, G.; Grunert, B. Z. Anorg. Allg. Chem. 1981, 473, 59–79.
(b) Graf zu Stolberg, U. Angew. Chem., Int. Ed. Engl. 1962, 1, 510–511.
(18) (a) Hengge, E.; Eibl, M.; Stadelmann, B. Monatsh. Chem. 1993,
124, 523–528. (b) Sakurai, H.; Tominaga, K.; Watanabe, T.; Kumada, M.
Tetrahedron Lett. 1966, 5493–5497 A note of caution: the preparation
described in ref 18b was utilized once successfully. However, the second time
the experiment was carried out the reaction mixture exploded, severely
burning one of the authors. As the exact cause of this explosion could not
be determined, we would caution against the use of this particular method.
(12) Dess, D. B.; Martin, J. C. J. Org. Chem. 1983, 48, 4155–4156
The Dess-Martin periodinane is currently commercially available (Sigma-
Aldrich).